Hydraulic hoist



Nov. 5, 1940. K. FEILCKE HYDRAULIQ HOIST File d Sept. 24, 1938 2 Sheets-Sheet 1 /Z. M cyllYl ENTkl -mlagm ATTORNEYS.

NOV. 5, 1940. FEILCKE Q I 2,220,815

HYDRAULIC HOIS'I I Filed Sept. 24, 1938 2 Sheets-Sheet 2 FIG 6 I/ a x ,R

IB s a;

,6 x I I2 INVENTOR.

M 56 BY @W; Jeim ATTORNEY.

Patented; Now. I

, i .rrmmmcnorsr ira-issuers, Galion, Ohio Application-September 24, 1938; Serial No. 231,589

This; invention; relates to, devices in which a force,- exertedbv either oneior more hydraulically; operatedrsjacks, disbursed; to; rotate a pivoted body,- and-where, this; force. varies in magnitude 5- owing-togthe changing; resistance of the a body to 1 itsrotation- A typical: examplevof such a device isa .hydraulichoist;forraising. the dump body of-a truck, forhere-the, load imposed upon the hoist mechanism is :much greater. at the start of -;"the dumping movement than attthe, finish. For

this reason-{the advantagesofmy invention are demonstratedxon a dumpibody-equipped with a hoist ofthedirectpushtype.

One object ormyinventionis to provide means '15 for applying the-hydraulicforce to the-pivoted body with greater efficiency'than heretofore on hoists of 1 this particular type, thereby reducing the-weight and cost; of the requir'ed machinery to 8.- minimum. 1 20- In: a: hoist offithedirect push type the, force exerted by the hydraulic Jack is directly applied to the =body,- and-the hoist 1 mechanism is oustomarilymountedqin the somewhat limited space betweenzthe body-floor: and the --top of the truck gs frame; -While: this-vtypes of; ,mountingvgreatly I facilitates: the-installationof: the hoist on. the truck, it..necessitateszthe-placing of the lack at an unfavorable angle withreferenc to the .body

' hinge and resultsiin-an ineflicient application of 30 the hydraulicforcez, To remedy this defect is the main object of myinvention;

A further object is -to slow down the speed a of rotationwhen" the resistance of thepivotedvbody is greatest, therebyreducing the energy to, be 35" supplied to;the-:h0.ist:during theperiod of severest operating; conditions.

Two; embodimentsnof" my invention arev illu stratedin the accompanying drawings, of which:

Fig. 1 is-.pa-rtiy.a-side view and partly a longi- 40 tudinalsectionthroughthe hoist mechanism and the body showing-thelatter-in-its down or loading position; I

' Fig; 2. showsthea same combination with the body -raised' tovan intermediate position.

45 Figiz3=shows the-same combination with the -illustratingwa combination in which the auxiliary jacks are larger in diameter than the main lacks.

In these drawings part Ill represents a supporting frame which contains the complete hoist mechanism and is mounted as an independent 6 unit on top of the truck frame, but in some cases p the supporting frame-may be a part of the truck frame itself. A dump body H rests with its longitudinal sills I2 on the frame .IO, being pivoted to the latter by means of the hinge pin 10:

I3, around which it can rotate until the dump position shown in Fig. 3 is attained. The body is equipped with the customary hinged tail gate 14 which opens when the body is tilted and permits the load to slide out. 15

The operating parts of my hoist mechanism consist of two cyilnders, each comprising a cylinder barrel, closed at one end, and a sliding piston rod within that barrel, which protrudes at the other end. The piston rod will be referred to as the pushing member, and the cylinder as the non-pushing or reaction member. The combination of cylinder and piston rod will be referred to as a hydraulicjack.

The main cylinder I5 is trunnioned at its lower end by means of the pin 16 in the frame Ill, and the piston rod I1 is trunnioned to the understructure of the body II by means of the lift pin [8. The auxiliary cylinder I9 is resting with the cross bar 20, which is part of its closed end; loose- 1y on the frame I!) in a predetermined position fixed by the link. 2|, the latter being pivoted on the cross bar 20 and with the pin 22 to the hoist frame Ill. The piston rod 23 of the auxiliary cylinder is also trunnioned to the body, preferably at the lift pin l8 of the main cylinder piston rod.

In Figures 1, 2, 3 only one main and one auxiliary cylinder are shown. For dumping heavy loads a plurality of main and auxiliary cylinders -40 placed symmetrically to the longitudinal plane through the center of gravity of the body may be used. Such an arrangement is shown in Figtires 6 and 7, where a pair of main and auxiliary cylinders is mounted on either side of the longitudinal plane A A through the center of the truck. l 1

Attached to the lower end of the main cylinder is the pump 24. This pump/is operated by means of the shaft 25 from the truck engine or any other available source of energy, and circulates the working fluid with which the system is filled. I

The turningv force R, exerted by the hoist mechanism, is the resultant of the forces created 5 by the two hydraulic cylinders l5 and I9; Cm being the force exerted by the: main cylinder l5 and Ca that exerted by the auxiliary cylinder l9.

These forces ar created by hydraulic pressure as follows:

The pump 24 draws the oil from the low pressure ends of the cylinders, i. e., the ends adjacent to the lift pin l8 through the pipes 26 and returns it under pressure through the pipes 21 to the high pressure ends of the cylinders, i. e., the ends adjacent to the supporting frame. This circulation of the working fluid is indicated by arrows in Fig. 1. The piston rods I1 and 23 move consequently, in their respective cylinders, away from the frame, pushing the lift pin i8 upwards and thus rotating the body on its hinge l3. Under pressure of the working fluid the piston rods move in their cylinders until they uncover the outlet ports 28 and 29 respectively, which permit the fluid to return through the pipes 26 to the pump. When these ports are uncovered the piston rods are held under pressure in their outward positions as long as the pump is working, and th flow of the working fluid under these conditions is indicated by arrows in Fig. 3. The movement of the piston rod is thus terminated by the same means in both cylinders.

As the auxiliary cylinder i9 is considerably shorter than the main cylinder IS, the former completes its stroke before the piston rod of the main cylinder has reached the end of its movement. The moment when the piston rod of the auxiliary cylinder has completed its stroke, i. e., when it has uncovered the outlet port 29, is shown in Fig. 2. From this point on, the auxiliary cylinder i9, while still under pressure, ceases to contribute a pushing force, is lifted off its seat on the supporting frame by its piston rod and is moved along with the body ii until the latter, kept turning by the force Cm, reaches the position indicated in Fig. 3. During the interval indicated by Fig. 2 and Fig. 3, the lower end of the auxiliary cylinder is guided by the link 2|. To accommodate the changing distance between the two cylinders the connecting pipes 26 and 21 are made of flexible material and are provided with sufficient slack in the down position to take care of the relative movement of the cylinder.

The lowering of the body to its loading position is accomplished in the conventional manner. A valve 30 operated through the rod 3| opens passages in the pump which permit the oil to flow in the opposite direction, 1. e., back from the high pressure sides of the pistons to thelow pressure sides. The weight of the body forces the oil to flow in this manner and the body settles gradually down to its loading position. During this lowering process the auxiliary cylinder is guided back to its starting position by the link 2|. A ball check and by-pass (not shown) are usually provided in the pump to permit the holding of the body in any desired intermediate position. The particular pump and piping arrangement shown is only one possible arrangement, and not 'an essential part of the invention as my device may be associated with any other suitable pump and piping lay-out, which will perform the functions described.

Fig. 4 is a diagram which shows how much is gained by this novel cylinder arrangement over the conventional direct push type hoist. The main cylinder I5, without the auxiliary cylinder 19, typifies a direct push type hoist. If this cylinder by itself has to produce the tangential force R required to turn the body, it would have to exert a force P as shown in the diagram. This force P has the desired tangential component R, but also an unwanted radial component S to the hinge pin I3, which merely increases the stresses in the parts and the friction losses. The same tangential force R, however, is produced with the two cylinders shown in Fig. 1 by the much smaller forces Cm and Ca and without added stresses and friction losses. The forces Cm and Ca have been superimposed on the forces P, R and S in Fig. 4, and acomparison shows that they are considerably smaller. As the pressures are alike in both cases it is obvious that the body can be turned by much smaller cylinders with my new hoist arrangement. While another shorter cylinder has been added as compared with the direct push type, there is a substantial net gain with my construction because weight and cost decrease approximately with the square of the cylinder diameters.

I have thus realized the main object of my invention, namely, to exert the hydraulic force with greater efliciency on a direct push type hoist, by adding to its cylinder a short stroke auxiliary cylinder at such an inclination towards it that the hydraulic force exerted by the latter creates a resultant with the force exerted by the main cylinder, which actssubstantially in a tangential direction to the lift pin are during the period of severest working conditions.

The second object of my-invention, the slowing down of the turning movement during the period of severe load, is to some extent, automatically attained by the addition of any short stroke auxiliary cylinder regardless of its position; for a pump of a given size will take more time to fill two cylinders than one, thus slowing up the turning movement while the auxiliary cylinder is in action.

, But .a study of Fig. 5 shows that the degree of inclination of the two cylinders toward each other has an important bearing on the rate of slowing down. In Fig. 5 the forces Cm and Ca.

are shown as they are exerted by the two cylinders under the conditions shown in Fig. 1, that is, with the cylinders inclined toward each other at the angle on. Also shown are two forces Cm and Ca which give the same resultant R with the cylinders inclined at an angle on. It is thus possible to obtain the same tangential resultant R with various inclinations of the auxiliary cylinder provided the forces exerted by the two cylinders are of the proper relative magnitude. While Cm and Ca are of the same magnitude, Ca 'is considerably larger than Cm. With equal oil pressure this means the auxiliary cylinder must diameters, producing the forces Ca and Cm,

is shown in Figures 6 and 7.

It is evident that the piston rods do not move at the same speed in both cylinders, that rod moving faster which has the least deviation from the tangent on the arc B-B described by the lift pin. In the starting position the piston rod of the auxiliary cylinder moves faster and the pump consequently has to fill up more of' the larger diameter cylinder at first. With the same amount of oil pumped per second this means a further slowing down of the turning movement when the cylinders are mounted with the included angle a', as compared with the arrangement shown in Fig. '1. 1

Choosing such an inclination between the cylinders that the largest auxiliary cylinder diameter possible under the circumstances is'required, is therefore the only means for attaining the second object of my invention, namely, to reduce the energy required to operate the hoist to a minimum.

Having thus described my invention, I claim:

1. The combination of a pivoted body with a hydraulically operated hoist mechanism mounted as an independent unit on top of the truck frame, said hoist mechanism comprising a plurality of jacks which are trunnioned with their pushing members 'to saidbody and placed in radial arrangement relative to each other, said jacks be ing located above the chassis frame to which the hoist mechanism is attached.

2. The combination of a pivoted body with a supporting frame and a hydraulically operated hoist mechanism comprising a plurality of jacks, all of said jacks being trunnioned with their I pushing members to said body, but not all jacks "prising a main jack and an auxiliary 'jaok, 'b'OtH .45

prising a main jack and an auxiliary ,jackfboth' trunnioned with their, pushing members to the body and mounted in radial arrangement relative tothe trunnion pin; the main Jack being trunnioned with its non-pushing member in the supporting frame, and the auxiliary jack being held in a predetermined contact position with the supporting frame by means connected with said frame.

5. The combination'of e. pivoted body with a hydraulically operated hoist mechanism comtrunnioned with their pushing members to the body; the main jack being trunnioned with its non-pushing member in the supporting frame, and the auxiliary Jack resting with its nonpushing member on said frame during the period of its activity, and rising up with the body after completing its stroke.

6. The combination of a pivoted body with a hydraulically operated hoist mechanism comprising a main jack and an auxiliary jack, both trunnioned with thelrpushing members to the body; the main jack being trunnioned with its non-pushing member in the supporting frame, and the auxiliary jack resting with its non-pushing member on said frame during the period of its activity, and rising with the body after com pleting its stroke, said auxiliary jack being guided during its movement by means connecting it with the supporting frame.

7. The' combination of a pivoted body with a hydraulically operated hoist mechanism mounted as an independent unit on top of the truckframe, said hoist mechanism comprising a plurality of jacks which 'are trunnioned with their pushing members to said body and placed in radial arrangement relative to such other, and symmetrically relative to the longitudinal plane through the center of the truck, said Jacks being located above the chassis frame to which the hoist mechanism is attached.

8. The combination of a pivoted body with a hydraulically operated hoist mechanism comprising a plurality of jacks of different lengths and diameters, said Jacks being trunnioned to thebody at the lift pin and arranged radially relative to said lift pin so that the resultant force exerted by the Jacks acts substantially at right angle to a line drawn through the lift pin and the body pivot.

9. A body hinged to a support, two hydraulically operated jacks of difierent engths arranged to turn the body on its hinge, both jacks being trunnioned to the body and mounted in radial arrangement relative to the trunnion pin, the longer jack being also trunnioned to the support and thus effective during the whole turning period, the shorter jack merely contacting the support and tree t'o"'rise with 'thebody when its' stroke is completed, thus being effective only during the early part of the turning period.

KARL FEILCKE. 

